In the above referenced patent application Ser. No. 11/067,099, there is discussed that an LPP EUV drive laser input window may consist of two windows: one for sealing, e.g., vacuum sealing, of the EUV Plasma production chamber and another one for exposure to the debris from plasma creation and that the cleaning of such debris inside the chamber may be accomplished, e.g., with a cleaning mechanism, which may incorporate, e.g., etching with a halogen-containing gas and/or by plasma etching.